Postnatal difference in calibre spectra between ankle extensor and flexor muscle nerves in cat.

Abstract

Calibre spectra were made on one ankle extensor (lateral gastrocnemius) and one ankle flexor (anterior tibial) muscle nerve. The nerves were always taken from the same side at corresponding proximo-distal levels in the same animal. The nerves were stained with osmium. During the earliest postnatal period, in comparison with the lateral gastrocnemius nerve, the anterior tibial nerve had: (1) the largest fibres and (2) absolutely and relatively more fibres bigger than 4 microns, (3) the peak shifted to larger fibres. It was concluded that at birth the anterior tibial nerve is more mature than the lateral gastrocnemius nerve. Further, it was shown that the differences between the two nerves in the newborn stage were eliminated when the animals reached an age of about one month. Possible correlation between morphological and functional maturity of central poitions of a reflex are and developmental stage of its peripheral nerve components was discussed.